This invention relates generally to an image forming apparatus, and especially to an apparatus for forming images using a combination of an electrophotographic process and an optical signal generator, such as an optical printer or copier.
Generally, printers and copiers can be separated into two categories, namely, those using face-up and face-down delivery systems. In the face-up delivery system, an image reproduced from an original is formed on a sheet of paper (i.e., a copy) and is dispensed from the apparatus face up. Since, each additional copy is dispensed on top of the previous copy, when a stack of originals is reproduced, a corresponding stack of images will be dispensed with the copies of the first and last originals at the bottom and top of the corresponding stack, respectively. The stack of images therefore, needs to be rearranged in order to place them in the same order as the stack of originals.
Face-down delivery systems overcome this drawback by dispensing each copy from the device face down. Therefore, a stack of originals and a stack of corresponding copies dispensed will be in the same paginal order.
Face-down delivery systems, however, are unable to reproduce images onto a recording medium such as an envelope or a piece of paper of equivalent or greater thickness without frequently curling and/or wrinkling such recording medium which often results in jamming the copier. More particularly, curling and/or wrinkling in a face-down delivery system is essentially due to the length of the path traveled by the recording medium (hereinafter referred to as "the paper transport path") and the two 90.degree. bends typically found in the paper transport path.
Face-down delivery systems also suffer from increases in production cost and first print time (i.e., total time required for reproduction of an original beginning with the print command and ending with the discharge of the image from the device). The complexity of the path traveled by the recording medium for purposes of maintenance is also quite undesirable.
Both face-up and face-down delivery systems typically employ cartridges which include various components used in the electrophotographic process. These cartridges, however, are often difficult to reach for purposes of maintenance and/or repair thereof. Therefore, an exceedingly large floor space which may be well beyond the physical size of the printer or copier itself is required to ensure access to the cartridge as well as other internal parts of the copier.
Additionally, in order to clear paper jams in both face-down and face-up delivery systems, an operator is normally required to stoop down into an uncomfortable position while placing his or her hand within the copier. Quite often the hand becomes stained from, for example, toner waste and/or dust. Still further, inasmuch as most of the interior of the apparatus is not easily visible even while in a stooping position damage to a component of the copier can occur while attempting to clear the paper jam.